Method of coating dentures to provide a polished surface

ABSTRACT

A method of treating the surfaces of preformed artificial prostheses, such as dentures, to produce thereon a finish coating and polish of pleasing appearance and improved smoothness and fit, which involves maintaining for a limited time contact between the surfaces and a heated liquid comprising a monomer of methyl methacrylate and, if desired, certain other additives.

United States Patent Tolosa [54] METHOD OF COATING DENTURES TO PROVIDE APOLISHED SURFACE [72] Inventor: Roberto Tolosa, 1318 East 4th Ave., Hi-

aleah, Fla. 33010 [22] Filed: Apr. 1, 1969 [21] Appl. No.: 812,295

[52] 11.8. C1. ..1l7/l38.8UA,117/64 R, 117/113, 117/119.6, 117/161 UB,32/2 [51] Int. Cl. ..A6lc 13/00, B44d 1/06, 844d 5/00 [58] FieldofSearch ..117/2 R, 138.8 UA, 161 UB, 117/113; 32/2 [56] ReferencesCited UNITED STATES PATENTS 2,622,991 12/1952 Sturm ..117/138.8 UA

[ Mar. 14, 1972 2,912,759 11/1959 Schlesinger ll7/l38.8 UA 3,084,0684/1963 Munn ..1 17/161 UF 3,485,662 12/1969 Metevia ..117/2 PrimaryExaminer-William D. Martin Assistant Examiner-Ralph HusaclcAttorneyMarkva, Smith & Kruger [5 7] ABSTRACT 9 Claims, No DrawingsMETHOD OF COATING DENTURES TO PROVIDE A POLISHED SURFACE BACKGROUND OFTHE INVENTION Artificial dentures have heretofore been formed on metalframeworks from polymerized substances such as methyl methacrylate.Dentures which incorporate these plastics have been found to have theadvantage of chemical stability as well as good mechanical strength.

The basic dentures generally are prepared by mixing polymers of, forexample, polymethyl methacrylates to form a paste with monomeric methylmethacrylates, and by hardening this paste in a mold under pressure andheat with the addition of polymerizing catalysts. The dentures so formedpossess the basic structure but tended to be rough and generallyunsatisfactory as a finished denture.

In order to improve the dentures, processes were developed in which thebasic denture was provided with a swelled lining of soft material havinggood physiological properties and chemical stability as well asmechanical strength. In order to provide these soft lining surfaces,mixtures of monomeric liquid polymerizable methacrylic acid and thepolymerization products prepare therefrom as, for example, polymericacid derivatives of monomeric methyl methacrylic acid, together withsuitable catalysts, such as organic peroxides, are packed inconventional dental molds and therein hardened under pressure and heat.Such lining may be of appropriate softness and resilience to avoid theirritation attendant upon contact of the hard parts of the dentures withthe mouth tissues and to provide improvement in the fit of the dentureswith the mouth tissues. The lining material for this purpose is quiteeffective, but it is clear that the process is quite complex, involvingmultiple steps and the handling of different dimensions so that thefinal lined product will have the proper fit.

The application of suitable linings may also be accomplished by amechanical process involving removal of an appreciable portion of thesurface and replacement thereof by a plastic coating. Such coating maybe formed by polymerization of a prepared polymerizable material, thepolymerization of which is aided by the use of heat and the presence ofa catalyst or activizer. The difficulty in this process is involved inthe maintaining of the critical fit dimensions which are necessary ifdentures are to hold their position and provide comfort.

ln the standard commercial process, it has been customary to prepare thedenture from a combination of metallic and plastic substances, thedenture being formed in a mold under heat and pressure and polymerizedto harden the final shape. The molds are made from the patient so as toachieve the desired close fit. The denture thus formed is accurate, butsomewhat rough and unpolished. Accordingly, it has been the priorpractice for a skilled technician using brushes, pumice stones and feltsand polishing substances to put the final polish or shine on thedenture. This required a high skilled technician so that the polishingand smoothing was accomplished without the removal of criticaldimensional material. This polishing process required at least tominutes. Even then, the result has not been as good as desired, and thiswas particularly true in prostheses having a deep or roof palate.

There has been a substantial need in the field for a simple, practicaland better method of providing the final shine and polish to the basiccast denture, without complex multiple dimension steps and withoutchanging the critical fit and shape dimensions of the denture.

OBJECTS OF THE INVENTION It is an object of the invention, therefore, toprovide a process for producing on a plastic denture or dentures, in amatter of seconds, a final surface coating of the desired smoothness andpolish, which is of better quality than that heretofore obtained withbrushes, pumice stones and felts by a skilled technician working by handfor a period of IO to 15 minutes.

Still another object of the invention isto produce by a relativelysimple commercial process a smooth and polished denture having a closefit, the addition or removal of critical dimensional material beingavoided.

Still another object of the invention is to provide a process wherein aneven better polish and finish may be provided on a basic dentureinvolving a time factor of only a few seconds as compared with the 10 to15 minute polishing time previously required.

Another object of the invention is to provide a process which isflexible enough to permit the polishing and finishing of one isolateddenture, or of a plurality of dentures simultaneously, therebysubstantially expediting the processing of a quantity of dentures andsubstantially reducing the time and skilled manpower required forprocessing a number of dentures.

DESCRIPTION OF THE PREFERRED EMBODIMENT In carrying out the presentinvention, the following procedure is used:

a. A preformed but unpolished denture (or dentures) is completelysubmerged in a boiling solution of the polishing liquid over a flamelessheat source. This liquid may vary in composition, but it is essentiallyliquid methyl methacrylate (monomer) to which there may be added apigment to create the proper color for prostheses, or a pine oil toprovide fragrance and additional smoothness.

b. The dentures are held in the actively boiling solution for a periodin the range of 10 to 15 secondsv c. The container is removed from theheat source, and the dentures are soaked in the hot liquid for a periodin the range of 20 to 30 seconds.

cl. The dentures are quickly removed from the liquid, placed on a cleanglass plate and dried, preferably in a current of warm, dry air.

The average time and the preferred time for the combination of boilingand soaking steps is therefore in the range of 30 to 45 seconds. Thetotal time should never exceed 60 seconds. During the period ofebullition, the vessel should be substantially but not completelycovered so as to reduce the loss of liquid by evaporation withoutexpansion explosion. Since the methyl methacrylate is a volatizableliquid which gives off inflammable vapors, the container must beprotected from flame or hot elements capable of causing ignition.

In the treatment disclosed, the denture as removed from the mold issubjected to polishing and cleaning action, without destroying thedesired close fit, and is sealed against the admission of food particlesand other minor foreign bodies and substances. The tooth structureparticularly is provided with a lining which is resilient and whichrelieves tenderness at pressure points on the gum tissues, whileproviding improved adhesion to the tissues.

At the conclusion of the soaking period, the dentures are normallylifted out with nippers, placed on a clean sheet of vitreous material,such as a glass sheet, and are exposed to a gentle, warm, drying currentof air.

The following examples indicate how the process can be carried out inpractice.

EXAMPLE I A liquid monomer of methyl methacrylate percent is placed in aclean container, substantially covered but not completely sealed, andthe liquid is quickly brought to a boil on a flameless heat source. Atebullition, the dentures are immediately completely submerged in theliquid and boiled for 10 to 15 seconds. The container is then removedfrom the heat source, and the dentures are permitted to remain submergedin the hot liquid for a period of 20 to 30 seconds. The dentures arethen quickly removed, placed on a clean glass plate, and exposed to acurrent of warm air until dry.

EXAMPLE u The same procedure of Example l is carried out, but the liquidused in a composition of the following proportions:

Methyl methacrylate monomer 1,000 cc Sudan lll (pigment) I drop of a lpercent solution Pine Oil 5 cc.

EXAMPLE III The method is carried out exactly as in Example 1 exceptthat the liquid has the following proportions:

Methyl methacrylate monomer 60% Methyl methacrylate (cross linked) 40%Since in the process of the present invention, a number of dentures maybe treated simultaneously, the total time for carrying out the cleaningand polishing process of the basic molded denture is considerablyreduced in contrast to that provided by the prior art wherein only onedenture at a time could be cleaned and polished by hand, each denturerequiring to minutes time of a skilled technician.

It will be evident that the process of the present invention can be usedfor a dental prosthesis having any combination of metal or otherstructural elements, as long as a substantial body portion of theprosthesis is formed of a polymerized methyl methacrylate, the saidsubstantial body portion forming the gum simulating area of the dentureor the parts of the denture which normally engage the natural gumtissues of the mouth of the wearer of the denture.

What is claimed is:

l. The method of surface treating a preformed denture structure having asubstantial body portion formed of polymerized methyl methacrylate,comprising the steps of:

a. immersing said denture structure for a period of up to 60 seconds ina bath comprising at least 60 percent liquid methyl methacrylate monomerbrought to ebullition, and

b. thereafter quickly removing said denture from said bath and dryingsaid denture.

2. The method of claim 1 wherein the said immersing time ofstep (a) isin a range of from 30 to 45 seconds.

3. The method of claim 1 wherein the drying of step (b) is achieved byplacing said denture structure in a gentle current of warm, dry air.

4. The method of claim 1 wherein said immersing step comprises immersingsaid denture structure in the liquid in ebullition over a heat sourcefor a period of 10 to 15 seconds, and

holding said denture structure in the liquid removed from said heatsource for a period in the range of 20 to 30 seconds.

5. The method of claim I wherein said bath further includes a minorportion of coloring matter.

6. The method of claim 1 wherein said bath further includes a minorportion of pine oil.

7. The method of claim 1 wherein said bath further includes asubstantial portion of cross linked methyl methacrylate.

8. The method of claim 7 wherein said methyl methacrylate monomer andsaid cross linked methyl methacrylate are in the proportion of 60percent and 40 percent, respectively.

9. The method of claim 1 wherein said bath comprises a combination ofthe following proportions:

a. methyl methacrylate monomer-1,000 c.c.

b. Sudan lll (pigment)l drop of a 1 percent solution c. Pine Oil-5 c.c.

2. The method of claim 1 wherein the said immersing time of step (a) isin a range of from 30 to 45 seconds.
 3. The method of claim 1 whereinthe drying of step (b) is achieved by placing said denture structure ina gentle current of warm, dry air.
 4. The method of claim 1 wherein saidimmersing step comprises immersing said denture structure in the liquidin ebullition over a heat source for a period of 10 to 15 seconds, andholding said denture structure in the liquid removed from said heatsource for a period in the range of 20 to 30 seconds.
 5. The method ofclaim 1 wherein said bath further includes a minor portion of coloringmatter.
 6. The method of claim 1 wherein said bath further includes aminor portion of pine oil.
 7. The method of claim 1 wherein said bathfurther includes a substantial portion of cross linked methylmethacrylate.
 8. The method of claim 7 wherein said methyl methacrylatemonomer and said cross linked methyl methacrylate are in the proportionof 60 percent and 40 percent, respectively.
 9. The method of claim 1wherein said bath comprises a combination of the following proportions:a. methyl methacrylate monomer- 1,000 c.c. b. Sudan III (pigment)- 1drop of a 1 percent solution c. Pine Oil- 5 c.c.